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Weights and Measures: Translating from Cups to Ounces

If you have ever read the food label on a can of nuts, you will recall that the portions are often listed in ounces—weighed ounces that is. Now many people have no sense of volume or number when they read ounces. And to make matters more confusing, a weighed ounce doesn’t always equal its volume equivalent.

And of course we are not just talking nuts here. This goes for a wide range of foods. Being one of the few countries still working in common measures, conversions between weight and volume can be downright confusing.

Although 8 weighed ounces of milk is very close to 1 cup (it is .93 cups) and for practical purposes we see the two as equivalent, 8 weighed ounces of flour is not; it is almost 2 volumetric cups). Different foods have different densities (the mass per unit volume) so a weighed ounce of different foodstuffs can have very different volumetric measures.

This can be a problem for people with diabetes who are trying to discern the carbohydrate content of foods. Even if you don’t have diabetes now, but it is in your family and you are trying to lose weight as a preventive measure, you need to know how many calories are in the amount of the food you are going to eat. If the label doesn’t list the quantity in an easily identifiable measure you may be up the proverbial creek.

Often nutrition reference guidebooks only give you the carbohydrate counts of foods in one measurement or the other. Usually this is the time when you have the measurement in some other descriptor. And being able to convert between volume and weight measurements is important if you cook, especially if you do so on a large scale.

In addition, many countries list bulk quantities (such as flour and sugar) only in weights, and when their citizens with diabetes come to the United States they are left a bit perplexed by our system.

Now if you know the density of a food, with a bit of math you can calculate its volume or weight. Thankfully there are numerouscookingwebsites that translate between volume and weight measures for you. Here you can find out the answer to questions such as how many teaspoons in a tablespoon and how many cups in 2 oz. of peanuts. (For the record 4.5 ounces will give you 1 cup, so 2 oz. will yield only .44 of a cup or a bit under ½ cup.

Or for all in one shopping, you can go to the USDA’s Nutrient Data Laboratory which allows you to choose between volume, count, and weight measures to find the nutrient composition of foods.

Which brings us back to those nuts I mentioned at the beginning: 1 oz, or approximately ¼ cup, (28.35 grams) converts to 20-24 shelled whole almonds, 14 shelled walnut halves or 18 cashews. Of course this is an approximation because it all depends on the size of the nuts.